Current grammatical treatment approaches for children with primary language disorder (PLD) yield only moderately significant gains after extensive treatment periods and are thus, inadequate. It is estimated that approximately 14% of kindergarten children have PLD, which includes children who exhibit significant weaknesses in language despite failing to meet criteria for intellectual disability. PLD negatively impacts early language development and has long-term detrimental effects on social interactions, academic work, and lifelong achievement. One of the core language weaknesses of children with PLD is poor use of grammatical forms with such weak- nesses persisting well into adolescence. One reason for the long-term negative effects of PLD may be that cur- rent grammatical treatments are using ineffective teaching approaches. Traditional treatments use inductive approaches (e.g., providing models of problematic forms at a high frequency) in which the learner is expected to implicitly acquire and generalize target grammatical forms. Evidence exists in other language-related disciplines that the inclusion of an alternative deductive teaching approach is more effective than inductive approaches alone. Unlike traditional inductive approaches, deductive instruction aims to make the learner explicitly aware of the underlying language pattern by directly presenting the pattern or pedagogic rule. The goal of the proposed study is to compare the efficacy of a traditional inductive approach to an approach that incorporates deductive instruction. This study is an integral component of a program of research focused on identifying effective and efficient interventions for children with language impairment. It is predicted that a combined deductive-inductive (D-I) approach will positively engage children's metacognitive processing skills and will lead to greater grammatical learning by children with PLD than an inductive-only (I-O) approach. Guided by strong preliminary data, this prediction will be tested through four specific aims: (a) to determine if a D-I approach is more efficacious than an I-O approach when teaching novel grammatical forms; (b) to determine whether gains made following D-I instruction are maintained over time; (c) to determine whether a D-I approach is differentially effective when teaching three novel grammatical forms; and (d) to determine if a D-I approach is differentially effective at teaching children with PLD who do and do not have significant language comprehension deficits. To address these aims, 60 5- to 7-year old children with PLD will be randomly assigned to either a D-I or I-O treatment. Participants in both groups will have the opportunity to learn three novel grammatical inflections. Learning will be assessed in terms of accuracy and response times' immediately following and 1-week post- treatment. To date, the primary emphasis on language intervention has been on inductive approaches; there- fore, the proposed evaluation of an alternative intervention approach represents an innovative shift in current clinical practice. The incorporation of deductive approaches may prove to positively impact the long-term out- comes of children with PLD and result in a transformation in clinical services.